The objective of the Multiphasic Checkup Evaluation Study is to test the efficacy of a general health examination, the Kaiser Multiphasic Health Checkup, in the prevention or postponement of illness, disability, and death. To this end, in 1974 a set of Kaiser Health Plan members ages 35-54 were essentially randomly allocated to two groups, each numbering approximately 5000 persons. Members of one group have been urged to have Multiphasic Heath Checkups annually while members of the second group have been left alone. Subsequent health outcome experience-specifically, outpatient clinic and pharmacy utilization, hospitalization, self-reported health status, and mortality--have been followed in comparable fashion for the two groups. These activities and the analysis of the results obtained are to be continued.